The present invention relates to communications systems. More particularly, it concerns optical communications systems for efficiently transferring various types of information including voice, video, digital and analog data.
Various communication system arrangements have been developed for effecting information exchange between distributed terminal devices. In the present telecommunications system, each user is assigned a unique address and is connected to a switching node which, in turn, is connected to other users and to other switching nodes. In order to establish a communications path between any two users in the system, one or more switching nodes must be configured to establish a pathway between an originating user and the destination user. In the electrical domain, switching devices and controllers are readily available for effecting signal routing between originating and destination points in the system. While a communications path can be conveniently established in a switched system, the bandwidth of the system is limited to the bandwidth of the particular signal carrier and the switches used to convey the information.
With the advent of communications at optical frequencies, information carrying capabilities far in excess of present telecommunications systems have become available. While an optical communications system can be designed to provide a switching arrangement analogous to the existing telecommunications network, the present inability of existing devices to effect switching at optical frequencies requires the optical information to be converted to the electrical domain for switching and then back to the optical domain for transmission. The present inability to effect switching in the optical domain greatly limits the effective utilization of optical communications technology, particularly in wide area networks.